Seal hanger



SEAL HANGER Filed Sept. 3. 1952 Patented Aug. '10, 1954 SEAL HANGERFrederick D. Moyer, Chicago, Ill., assigner to Chicago Bridge & IronCompany, a corporation of Illinois Application September 3, 1952, SerialNo. 307,655

7 Claims. 1

This invention relates to a seal hanger and more particularly to ahanger device for supporting a. sealing ring about the periphery of ailoating roof in a liquid storage tank.

The storage of crude oil, gasoline and other petroleum products alwayspresents the problem of evaporation and loss of marketable product,which in some instances, has been solved by the provision of iioatingroof storage tanks. These tanks are cylindrical open-topped tanks ofconsiderable size. The iioating room is, as its name implies, a closurewhich is buoyant and rises and falls with the liquid level in the tank.Ordinarily the roof is slightly smaller than the inner diameter of thetank leaving an annular space between the roof and side walls when theroof is centered in position. This space must be sealed and is usuallyprovided with means to accomplish such result.

One of the most effective methods of sealing the space about a iloatingroof is by using a ring of relatively thin material and holding thisring in sliding contact with the tank side walls. With the ring in suchposition, a gas imperviousriiexible sealing material may be bridgedbetween the ring and the roof to seal the space therebetween. Thepresent invention is concerned with the devices used in supporting sucha sealing ring.

The invention will be described in a preferred embodiment by referenceto the accompanying drawing in which the gure illustrates a brokenvertical section through the periphery of the floating roof and theadjacent tank sidewall, illustrating one seal hanger in operativeposition for supporting the sealing ring against the side walls.

The figure of the drawing shows the tank side wall l which is composedof plates given a ourvature to conform to the cylindrical curvature ofthe tank. Liquid Il is shown within the tank and oats a closure membergenerally designated a oating roof i2. The particular roof illustratedhas plates I3 forming a top deck, plates I4 forming a bottom deck and anupstanding substantially vertical rim i5 which is joined to the top andbottom decks to form a liquidtight enclosure. The top and bottom decksillustrated may be part of a pontoon or simply the structures of adouble deck roof without affecting the particular application of theseal hanger to be described. Ordinarily all oating roofs are providedwith an upstanding peripheral rim i 5 to give the roof a draught and toprovide the roof with a capacity for storing rain water.

The sealing ring generally designated I6 is preferably constructed inaccordance with the teachings of Goldsby and Orr Patent No. 2,586,813,issued February 26, 1952. This is made up of a number of shoes definedby portions of the ring between vertical extending exures.

The ring can ride against the side wall to provide a seal therewith andthe flexures permit the ring to change its shape in response to a changein the shape of the side wall section against which it is pressed.

A sealing fabric I1 extends from the upper edge of the sealing ring tothe peripheral upper deck edge of the floating roof. The fabric ispreferably gastight and may be made of cloth impregnated with asynthetic rubber composition. This seal is provided with suicient lengthto permit the roof to move toward and away from the side walls of thetank without damaging the material.

The supporting device for the sealing ring, as illustrated in the gureof the drawing, rests mainly between the rim l5 of the floating roof andthe side wall of the tank. The support for the sealing ring is providedby a lever and a link. Lever 2i) may be called an L-shaped member inthat it has an integral leg or arm 2l extending inwardly under the roof.The level1 20 is pivotally attached to the sealing ring at 22 and eX-tends downwardly to the lower portion of the roof where a pin 23 whichis secured to the lever 20, is caught in a vertical slot 24 formed by X-ture 2E attached to the lower portion of the roof rim i5. Thus, it willbe obvious that the lower portion of lever 26, may travel vertically bymoving the pin 23 in the slot 24 and may pivot about 22, its attachmentto the sealing ring. The purpose of this type of connection will beobvious from the following description.

The link .30 is pivotally secured to the upper portion of the rim at 3land is pivotally attached to substantially the mid-point of lever 20between the points 22 and pin 23 on the lever 20. This point is shown at32, it being understood that suitable brackets and pin connections areprovided at the points indicated.

The pivotal connections of each of the lever and link respectively tothe sealing ring and to the floating roof, namely points 22 and 3|, arein the same horizontal plane. The pin 23 which travels in slot 24, isvertically aligned with the pin 3| and retains this alignment at alltimes. This construction permits the roof to move laterally of the sidewall of the tank without changing the vertical position of the sealingring with respect to the side wall. Stating this proposition in anothermanner, the sealing ring willnot slide upon the side wall surface merelybecause the roof changes its position within the tank such that it movescloser to one side of the tank and away from the opposite side. Uponsuch movement of the roof, the pin 23 on lever 29 merely travelsvertically in the slot 24 and the sealing ring maintains its samerelative position.

The seal hanger is provided with means for pushing the sealing ringagainst the side Wall and at the same time, providing a force to centerthe roof within the tank. In the illustrated embodiment, these forcesare provided by a tension coil spring 49. The integral arm. 2-l on lever2a extends under the roof to a point where its inner end 26 ispositioned under a cylindrical well 4l formed through the decks of thefloating roof; A link 43 is pivoted at 44 to the arm 2l and extendsupwardly within the well to a connection at 45 with the spring 4B. A-short link 46 provided with lock nuts 41 atfitsupper end. bears againsta cap 48 on the yell to hold the spring in tension. An adjustment isprovided by the nuts 41 to vary the pull of the coil spring.

In order to fully understand the operation of the forces provided byspring 4%, a mathematical consideration of the forces acting on thehanger may clearly demonstrate that a centering force is provided andthat the force pushing the sealing ring against the side wall isindependent of the Weight of the sealing ring or any forces acting. inthe plane of the ring. These latter forces might be friction between thesealing ring and. side wall orresistance to movement caused by aprotuberance on the side wall coming in contact with the sealing ring.For purpose of this illustration let W equal the weight of the sealingring acting downwardly,

F equal the pull of the spring upwardly on the link 43,

l-I- equal the horizontal distance between the line of action of theforce F and the pin 23 in the slot 24,

It equal the distance between the pivotal connections respectfully oflever 2l] and link 30 to thezsealing ring and the roof, and

V equal the vertical distance between the pivotal connection 22 of lever20 to the sealing ring and the pin 23 in the slot 24.

These forces will result in an upward force on the pin 3l connectinglink 3u to the roof of W minus F. In solving the balance of force on thehanger let R1 be equal to the force directed on the pivotal connection3l inwardly on the roof and outwardly on the hanger system;

R2 be equal' to the force on the pin 23, inwardly on the roof andoutwardly on the lever 2B of the hanger and.

R3 be equal to the force inwardly onv the hanger system and outwardly onthe sealing ring directed at ,the pivotal connection 22.

The equation of moments about the pivotal connection 32 considering theforces on the lever 20 is:

rIihe equation of moments about the pivotal connection 3| on the wholehanger system is:

Toviind R3 consider the horizontal forces on the hangerl system as beingin equilibrium. This gives:

R3 is the horizontal force at the pivotal connection 22 on the sealingring. It will be noted thatthe forceF provided by the spring will varyinversely with relation to the distance. between the sidewall and roof,designated h. I-I varies very slightly and V varies also slightly. Thecoil spring 40 is chosen so that the force it provides variesconsiderably faster in proportion than does thev distance h. Inthismanner a centering force is built into the hanger for keeping the roofautomatically centered within the tank. When the roof moves toward oneside of the tank, the force pushing` the sealing ring against the sidewall increases considerably at that side of the roof and correspondinglydecreases at the diametrically opposite side of the roof, thus returningthe rooiflto its center position.

It will also be noted from a considerationA of the force Re pushing thesealing ring against the side wall, is totally independent of W', whichis the weight ofthe sealing ring or any force. acting in the plane ofthe sealing ring.. Thus the. ring is always forced against the. sidewall with the same force irrespective of whether frictionA is greater orlesser than at other times and irrespective of the weight of the ring.The ring is alwaysV held inl the same vertical position with relation tothe roof without regard to kthe position. of the roof within the tank.These advantages contribute to longer life for the sealing ring andinoresuccessful operation of the sealing of the floating roof tank againstthe sidewalls of the tank.

While I have shown and described certain embodiments of my invention, itis to be understood 'that it isy capable of many modifications. Changes,therefore, in the construction and arrangement may be made withoutdeparting from the spirit and scopeof the invention as disclosed intheappended claims.

I claim:

l. A hanger for supporting a sealing ring about the periphery of afloating roof in a liquid storage tank, comprising, a substantiallyupwardly extending lever pivotally connected to the ring and verticallyslidably and pivotally connected to the roof, a link pivotally connectedto -the roof and pivotally connected to the central. portion of saidlever, the respective pivotall connections of said lever and link'to theroof and ring being in the same horizontal plane whereby no verticalforce in the plane of the ring affects the pressure between the ringland tank, an inwardly extending arm on the lower end of the lever and acoil spring secured to the inner end of said arm and to the roofproviding an upwardly directed force on the arm pushing the ring againstthe tank through the lever and link.

2. A seal hanger for supporting a sealing ring about a floating roof incontact with side walls of a liquid storage tank, comprising, a leverpivotally connected to the sealing ring and vertically slidably andpivotally connected to the roof therebelow, a link pivotally connectedto the roof in the same horizontal plane as said pivotal connection ofsaid lever'and pivotally connectedy to the central portion of saidlever, said pivotal connection to the roof and slidable connection tothe roof being in the same vertical plane, an arm on said. leverextending inwardly under the roof, and spring means connected to saidarm andsaid'. roof providing an upwardly directed force on the arm tourge said ring against said tank side walls through said lever and link.

3. A hanger. as specified in claim 2. wherein said spring means providesa force substantially inversely proportional to .the distance betweenthe horizontally aligned pivotal yconnections of said lever and link.

4. A hanger as specified in claim 2 wherein said arm is integral withsaid lever and means are provided for varying the force o-n said arm.

5. In a liquid storage tank having a iioating roof and one or more shoesadapted to slidably contact the inner side walls of the tank, a sealhanger comprising a generally L-shaped member having one leg pivotallysecured to a shoe and the other leg extending inwardly under the roofwith the angle of the L being vertically slidably oonnected to the roof,a link pivotally connected to the roof in the same horizontal plane asthe pivotal connection of the L-member to the shoe and pivotallyconnected -to the L-member substantially midway between its pivotal andslidable connections whereby no vertical force in the plane of the shoeaffects the pressure between the shoe and the side walls, and springmeans connected to the inwardly extending leg of the L-member yieldinglyurging said leg upwardly to press the shoe against the side walls.

6. A seal hanger as specied in claim 5 wherein said spring means ispositioned in a well in the roof and is connected to a pair of rods, onepivloted to the L-member and the other connected to the roof withadjustable means thereon for varying the force supplied by the springmeans to the L-member.

7. A seal hanger as specified in claim 5 wherein said spring meansincludes a coil sp-ring capable of providing a force that increases at aproportionally greater rate than the rate at which the distance betweenthe roof and shoe decreases when the hanger is in use.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 2,471,404 Boberg May 31, 1949 2,542,444 Wilkin Feb. 20, 19512,554,497 Moyer May 29, 1951 2,576,136 Moyer Nov. 27, 1951 2,587,508Moyer et al Feb. 26, 1952

